In the grey flesh fly, Neobellietia bullata, vitellogenesis is cyclic. The repeated gonadotropie cycles suggest that egg development is under hormonal regulation. Previously, it has been shown that egg development in flies and mosquitoes is regulated by ecdysone and juvenile hormone (Huybrechts and De Loof, 1977, 1981; Hagedom et at., 1975; Borovsky et al. 1985), which are synthesized by the ovary (Goltzene et al. 1978; Hagedorn et al. 1975; Borovsky et al. 1992a, 1992b, 1993d). Neurosecretory cells in the brain usually produce peptide hormones. Two of these peptides, EDNH and allatostatin, control the synthesis of ecdysone and juvenile hormone (Hanaoka and Hagedom, 1980; Woodhead et al., 1989). In addition, a 65-amino acid peptide, ovary maturing parsin, which acts as a true gonadotropin and stimulates vitellogenin biosynthesis has been recently isolated from the brain of Locusta migratoria (Girardie et al. 1991).
Less information is available about the signals that terminate vitellogenesis. An oostatic factor synthesized by the mosquito ovary was recently purified and sequenced from female Aedes aegypti (Borovsky et at. 1990, 1993a). The factor, which is a decapeptide, was named Trypsin Modulating Oostatic Factor (TMOF), and its amino acid sequence was determined as NH.sub.2 -YDPAPPPPPP-COOH (See U.S. Pat. No. 5,011,909). However, this peptide was not found in Neobellieria. We found a completely different hormone in Neobellieria.